[SERVER-4689] When Journaling is Activated - I/O spike occurs on NFS filer and VM Created: 16/Jan/12  Updated: 29/Oct/13  Resolved: 20/Jan/12

Status: Closed
Project: Core Server
Component/s: Storage
Affects Version/s: 1.8.0
Fix Version/s: None

Type: Bug Priority: Major - P3
Reporter: Wireless Matrix (SOC) Assignee: Mathias Stearn
Resolution: Incomplete Votes: 1
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified
Environment:

Linux, Netapp, WAFL Filesystem


Issue Links:
Related
related to SERVER-5429 NFSv3 & NFSv4 support for MongoDB wit... Closed
Operating System: Linux
Participants:

 Description   

When journaling activated in our replica sets, the MongoDB servers generate out of the ordinary I/O. This causes I/O wait to spike and the number of IOPS on our filerhead to grow rapidly.



 Comments   
Comment by Mathias Stearn [ 20/Jan/12 ]

This will get folded into our broader effort to better support NFS.

Comment by Wireless Matrix (SOC) [ 20/Jan/12 ]

You can close this ticket, but please ensure that this is on your product roadmap, as we know more and more companies are using NFS datastores in conjunction with MongoDB.

Comment by Mathias Stearn [ 20/Jan/12 ]

Do you need any more info or can I close this ticket out?

Comment by Mathias Stearn [ 18/Jan/12 ]

It's not, that was a separate issue relating to allocating datafiles.

I remember that we ran into this while testing this a while ago. IIRC, my theory at the time was that linux had different behavior for private mmaps backed by nfs than for either privated disk-backed mmaps or shared nfs mmaps.

The current recommendation is to use iSCSI or local storage (better) for mongod servers rather than nfs. We are currently working to improve the performance on nfs, but that will only apply to the 2.2 release and will not be backported to the 1.8 series.

PS - On a related note, I would suggest upgrading to (at least) the latest 1.8 release as there have been some important bugs fixed since 1.8.0.

Comment by Eliot Horowitz (Inactive) [ 16/Jan/12 ]

Might be related to SERVER-4652

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